The ratio of carbon-12 to carbon-14 at the moment of death is the same as every other living thing, but the carbon-14 decays and is not replaced.

So, if you know the radioactive isotope found in a substance and the isotope's half-life, you can calculate the age of the substance. Well, a simple explanation is that it is the time required for a quantity to fall to half of its starting value.

So, you might say that the 'full-life' of a radioactive isotope ends when it has given off all of its radiation and reaches a point of being non-radioactive.

The use of various radioisotopes allows the dating of biological and geological samples with a high degree of accuracy.

However, rocks and other objects in nature do not give off such obvious clues about how long they have been around.

So, we rely on radiometric dating to calculate their ages.

The evidence against a recent creation is overwhelming.

There is perhaps no greater attack on science than Young Earth creationism (YEC).